The 2011 Subaru WRX STI marks the return of the sedan bodystyle to the STI family.

SUBARU WRX STI REVIEW

Subaru Australia has diversified its WRX STI range for 2011, with the addition of an automatic transmission and a sedan body style effectively tripling the number of STI-badged models.

Not only that, but a significant number of suspension upgrades have been made to the 2011 Subaru WRX STI’s undercarriage.

The result is a performance car that handles better, has broader aesthetic appeal and is now more versatile than ever before.

It’s also $2000 cheaper than the MY2010 STI, with both auto and manual models retailing for $59,990.

To celebrate the arrival of the new range, Subaru invited TMR to Victoria's Phillip Island Circuit. Here we were able to put both manual and automatic variants of the STI sedan to the test.

Our interest was piqued most by the automatic version of the STI.

Based on the WRX STI A-Line model that’s sold in the Japanese domestic market, the automatic STI has a conventional five-speed hydraulic auto in place of the standard six-speed manual.

A tiptronic gate and a pair of column-mounted paddle shifters enable manual control of ratios, and the gearbox is programmed to match revs on downshifts to reduce drivetrain shock.

But, as we found out, it’s no match for the six-speed manual out on the track.

Conditions were optimal at Phillip Island. Visibility was excellent, the tarmac dry and the track was entirely open, with no cones to spoil the fun.

We started the day at the helm of an auto-equipped STI sedan. Exiting from pitlane and through Phillip Island’s sweeping right-hand first turn, the auto STI delivered its 221kW to the road smoothly and progressively.

Upshifts, whether done automatically or manually, are direct and don’t interrupt the supply of power. While this is good, changes aren’t, however, as fast or as crisp as those of the Lexus IS F’s eight-speed auto.

The real downside of the auto box (for rapid track work) doesn't take long to appear - on Phillip Island's circuit as early as turn two: a long, double-apex left-hander that is hard to master.

Pulling back the left paddle to knock the transmission down a couple of ratios elicits a nicely-matched throttle blip, but the speed of the shift isn’t quite fast enough.

The gap between the auto’s second and third gear also means most corners are exited in third, leaving the STI’s 2.5 litre engine out of the meat of its power band. (Speaking of which, the auto-equipped STI has its torque output cut back to 350Nm, 57Nm less than the manual model.)

On the upside, cornering grip under neutral throttle is excellent.

Subaru has comprehensively re-worked the STI’s suspension with new bushings, new damper tunes, revised springrates and a 5mm lower ride height.

The STI handles direction changes very well, and feels astonishingly nimble for a car with so much weight ahead of its front axle.

Feed in some power just before hitting an apex though, and the inside front wheel starts to struggle for grip.

Automatic STIs are only fitted with a viscous LSD at the rear, with the front diff being an open type. The result is reduced traction under power - particularly when one side of the car is loaded up mid-corner.

The contrast between the performance of the automatic and the manual is surprisingly stark. After pitting in and exchanging the auto for the six-speed, the difference between each is very noticeable.

For one, the extra torque of the manual gives it an edge in straight-line acceleration. Once above 3500rpm, power delivery is very strong and delivers a substantial shove in the back.

The close-ratio six-speed and shorter final drive ratio also enables you to keep the engine on song. The result is that the manual version of the STI feels a great deal more rapid than the automatic.

The manual receives the same suspension tweaks as the automatic, but its driveline benefits from a few significant improvements that aren’t present on the auto. Namely, the front helical limited-slip differential, the Torsen rear LSD and the Driver Control Centre Differential (DCCD), which gives the driver some control over the front-rear torque split.

Each of the three differentials enhance grip when under power, giving the manual substantially more traction than the automatic.

The DCCD system, which isn’t available on the auto, enables the driver to move the torque bias further to the rear, helping rotate the STI into corners.

Conversely, the DCCD system can direct more torque to the front wheels to improve control in wet conditions. It can also be left to its own devices in ‘auto’.

Braking performance also seemed better in the manual, even though both transmissions have the same four-piston Brembo brake package.

The auto felt a little squirmy under hard braking, whereas the manual seemed more composed.

For all their dynamic differences, there is little difference in speed between either transmission; by the end of the front straight both were traveling at just over 210km/h.

However, the manual’s greater torque and limited-slip differentials allowed it to pull out of corners harder and faster, making it by far the quicker track car.

TMR Verdict

Subaru Australia says demand from dealers suggests up to 70 percent of STI sales will be for the auto, but our first taste of the automatic-equipped STI on the track left us underwhelmed.

We can understand why some might want the auto – after all, it would be easier to live with in peak-hour traffic – but for buyers wanting their STI as a weekend warrior rather than a workday hack, we’d recommend they stick with the manual.